Electric heater



May 29, 1928. 1,671,378

F. D. PITT ELEGTRI C HEATER Filed June '7, 1926 2 SheetsSheet l INVENTOR 5350 6/70; D. P/li A TTORNEY May 29, 1928.

F. D. PITT ELECTRIC HEATER 1926 2 Sheets-Sheet 2 INVENTOR ATTORNEY Filed June Patented May 29,1928. 1,671,378 i ,UNITED STATES PATENT OFFICE.

FREDERICK D. PITT, OF KANSAS CITY, MISSOURI, ASSIGNOR TO THE ANDERSON-PITT CORPORATION, OF KANSAS CITY, MISSOURI, A CORPORATION OF MISSOURI.

ELECTRIC HEATER.

Application filed June 7, 1926. Serial No. 114,175.

My invention relates to electric heaters and the heating element support and the portion 65 more particularly to the heating element of of the bracket engaging therewith. an electric heater and supporting means Fig. 6 is a diagrammatic view of the retherefor. flection of rays from the heating element by It is a purpose of my invention to provide the reflector to a surface to be heated.

a heating element for a heater that so Referring more in detail to the drawings: so constructed that the entire heating element My improved electric heater comprises a faces the reflector of the heater so that the base member 10 upon which is mounted a heat radiated from the element is all re-' bowl-like reflector 11, the same being secured 1 flected outwardly by the reflector. The heatadjustably to the base member by means of ing element is furthermore preferably so a bracket 12 engaging with the standard 13 mounted relative to the focus of the reflector and being held in adjusted position by means that the'various portions thereof are as near of the clamping screw 14. The bowl-like the focus of the reflector as they can be reflector element is provided with the usual 1 placed. It is also a purpose of the invention peripheral groove 15 for holding the guard to shape and relate the reflector and the member in position, the guard member being 70 heating element for heating equally all poromitted from the drawings to more clearly tions of a surface having a predetermined show the internal construction of the heater. area spaced a predetermined distance from Secured to the rear face of the bowl member the heater. 11 is a canopy 16 into which the cable 17 ex- More particularly it is a purpose of my tends in which the conductors 18 and 19 are 75 invention to provide a heating element and provided. a support therefor which support has a sup- Secured to the reflecting element 11 in any porting surface facing the reflector, said supsuitable manner, as by means of the rivet porting surface being provided with faces :20, is a bracket member having a standard thereon defining a grooved seat which is sub- 21 which is substantially tubular in form and 80 stautially in the form of a spiral and upon which is split at the upper end thereof to which a heating element which is continuous provide the diverging arms 22 which have from one end to the other end of the spiral the upwardly extending portions 23 thereon so is mounted. The heating element is preferthat are curved substantially on the are of a ably zigzag or sinuous in form instead of circle and which terminate in the outturned a5 coiled, so that the same will lie flatly in the lip 24 extending in opposite directions. A grooves. transversely extending bracing element 25 Other objects and advantages of the invenhaving the reduced tongues 26 on the ends tion will appear as the description of the thereof engaging in the slots 27 in the arouaccompanying drawings proceeds. However, ate portions 23 of the arms provided on the go I desire to have it distinctly understood that bracket, is provided to strengthen the bracket 1 do not intend to limit myself to the exact at the upper end thereof. details shown Or described, but that I intend Mounted upon the bracket member is a.

to include as part of my invention all such heating element support 28 which is preferobvious changes and modifications of parts ably of refractory material which is also 95 as would occur to a person skilled in this electrical insulating material and which is art and as would fall within the scope of the provided with the recesses 29 which, as clearclaims. ly shown in Fig. 5, do not extend entirely In the drawings: through the wall of the element 28, into Fig. 1 is a perspective view of my imwhich the outturned end portions 24 of the oo proved electric heater. bracket member extend, thus supporting the Fig. 2 is a vertical sectional view thereof. heating element supporting member 28 upon Fig. 3 is a perspective view of the heatthe bracket. The heating element supporti ing element support and portions of the suping member 28 is further preferably notched porting bracket therefor separated. as at 30 to accommodate the tubular portion Fig. 4 is a fragmentary detail view of the 21 of the bracket. The heating element supheating element,-and port is spheroidal in contour and is provided Fig. 5 is a fragmentary sectional view of with faces 31 which collectively form a spiral ing element mounted upon the spiral face bent in a zigzag or substantially sinuous on the member 28 from vthe opposite ends thereof.

The spiral face 31 is substantially straight across transversely of the element as viewed in Fig. 2, thus providing shoulders at opposite sides of the face and forming in effect a spiral groove for receiving the heating element. .The heating element 36 is preferably made of a suitable resistance wire which is shape so that the element as formed is sub stantially straight transversely of the element and when placed in position in the spiral groove on the supporting member 28, will lie substantially flatly against the bottom of said groove. One end of the heating element 36 lies substantially opposite the opening 37 provided in the supporting member 28, and adjacent said opening is a similar opening 38. The conductor 19 extends through the opening 38. in spaced relation to the end of the heating element 30 and through the opening'37 where the same is connected with the one end of the heatingelement. The heating element then continues in' a generally spiral form to the shoulder 35, an opening 39 being provided through the supporting member 28 through which the other conductor 18 extends, this conductor being secured to the end of the heating element 36 adjacent the shoulder 35. The conductor 18 also extends through a substantially central opening 40 in the supporting member 28 and out through the end 33 thereof, said conductors 18 and 19 extending throu h the bowl 11 and being provided with suita le insulating sleeves 41 where the same extend through said reflector bowl. As will be. evident from Figs. 1 and 2, the supporting member 28 is substantiall cupshaped, being provided with a hol ow or chamber 42 therein so as to make the same relatively light and furthermore to accommodate the portions of the bracket mounted within the same and for passage of the conductors 18 and 19 inside said supporting member.

The reflector and-the heating element are shaped and related as described and illustrated, for the purpose of heating substantially' equally al portions of surfaces exsed to the heater at a desired distance in ront of the heater. The surface to be beated may be considered as included in a vertical plane per endicular to the axis of the reflector and, or example, six feet wide, six feet hig and located six feet from the reflector. The use of the principles whereby a heater is provided to efiect such result is illustrated in Fig. 6, A of which represents the center point of a limited vertical circular plane having a three-foot radius AB. The reflector 11, having the reflecting surface C, which is preferably ellipsoidally concave and has a focal point D or so-called true focus on the axis of the curve, is so positioned that its extended axis contains the point A, and said focal point D of the reflector is substantially six feet from the point A.

For purposes of illustration, a source of rays, E, is assumed to move over the vertical circular plane representing the vertical surface area to be heated. E is-initially posi-;

tioned in the circumference of the plane and is then assumed to move on the circumference of the plane, and so describe a circle. The assumed rays from the moving point .E that reach the reflector are reflected there from to foci of the reflector that lie in a circular line indicated by the vertical diameter line FG, said circular line defining substantially the location of the outer boundary, that is, the margin or periphery, of the heating element. The ray-projecting point E is then assumed to move over the entire surface of the vertical area circumscribed by the circle indicated by BE, to project rays to the reflector for reflection to numerous foci of the reflector. Numerous rays are projected by the point E from each position that it occupies, all portions of the reflector receiving rays projected from each position; and all the rays projected from a particular position which reach the reflector are reflected to one point in-space, that is, are concentrated in one point, i. 0., one of the numerous foci of the reflector, one being said focal point D of the reflector. The foci thus identified define and lie in a convex surface containim substantially all of the foci for the rays fiom said limited vertical area that are receivedby the reflector.

The heating element is then arranged substantially over and substantially conformable to said convex foci-containing surface established by said assumed moving rayprojecting point E, and therefore is substantially entirely in focus with the reflector; whereby the converse phenomenon to the assumed phenomenon will occur, namely, the rays of heat projected from the element and received by the reflector, will be reflected to foci such as E, A and B on the area to be heated, indicated by B-E, and the said foci will be equalldistributed over the area BE so that all portions of the area will receive equal amounts. of rays and will be equally heated. The heating element as thus provided will have a convex surface facing the reflector curved substantially complementarily to the reflector, and, therefore, preferably ellipsoidal; the axis of the convex heating element will lie in the axis of the reflector, and the apex of the heating ele ment will be positioned adjacent the true focus, or focal point, of the reflector.

The heating element is preferably supported, as described, on a cup-like core, the core being constructed to conform substantially to the surface comprising the location of said foci of rays assumed to be projected from the area to be heated to the reflector. The element is substantially uniformly distributed over the convex face of the core to substantially cover the face whereby substantially all the heat rays from the element are projected directly to the reflector, or reflected by the core to the reflector, so that substantially all the rays emitted by the element are reflected to the area to be heated, for maximum utilization of the reflecting surface and heat en- 'ergy of the element for maximum and equal heating of the area to be heated.

I prefer to establish the curve of the re- 1 flector as the end portion of an ellipsoid of revolution, the end portion having a focal point adjacent the reflecting surface, the center point of the plane to be heated beihg the focal point of said ellipsoid opposite to the focal point of the reflector portion, and the axes of the reflector and the heating element lying in the major axisof the ellipsoid of revolution.

What I claim and desire to secure by Letters Patent is: 1. An electric heater comprising a reflector, a heating element including a cupshaped core having its closed end facing the reflector, a resistance wire coiled on the surface of the core, and a standard on the reflector having attaching arms located within the open end of the core.

2. An electric heater comprising a reflector, a heating element including a cupshaped core having its closed end facing the reflector, a resistance wire coiled on the surface of the core, a standard on the reflector having arms located within the open' end of the core, and a brace spreading the arms to holding contact with the core.

3. An electric heater comprising a reflector, a heating element including ,a cupshaped core having its closed end facing the reflector, a resistance wire coiled on the surface of the core, a standard on the reflector having arms keyed to the core Within its open end, and a brace keyed to the arms and extending therebetween to retain the arms in holding contact with the core.

4. A heater comprising a reflector, and a convex heating element having its surface substantially in focus with said reflector.

5. An electric heater having a concave reflector any cross-section of which is substantially a portion of an ellipsoid of revolution, an electric heating unit therefor any cross-section of which is substantially a portion of an ellipsoid of revolution and having a convex face substantially conforming to the concave reflecting surface of the reflector, and means for mounting said heating unit with its face substantially in focus with said reflector.

6. In combination with a heater having a concave reflector comprising a surface adapted to reflect rays received from points in the axis of the reflector to a focal point in said axis, a heating element mounted in front of the reflector and axially thereof, the heating element having a convex face, the apex of the heating element being positioned substantially on said focal point of the reflector.

In testimony whereof I afiix my signature.

FREDERICK D. PITT. 

